Plastic bags for vacuum packing

ABSTRACT

The plastic bag for vacuum packing provided by the present invention has embossments which space in longitudinal direction and stagger in transverse direction formed on the inner surface, and thus lots of intercommunicate channels are formed so as to eliminate the possibility to form any air pocket or internal cavity. Meanwhile, air linearly exits from the bottom to the open end, so it takes less time to evacuate the bag. Further, the bag only has one film be embossed, and thus the manufacturing process thereof is simplified and at low cost, and the bag is easy to wash. Moreover, the strength of the bag provided by the present invention is enhanced; especially the anti-avulsion capability is well improved.

FIELD OF THE INVENTION

The present invention relates to packaging materials and, in particular, to a plastic bag for vacuum packing.

BACKGROUND OF THE INVENTION

Vacuum packing is a common method for storage, in which, a bag is evacuated to prevent decomposition or oxidation of the item therein by the ubiquitous bacteria in the air. Generally, when a user desires to vacuum pack food or the like using a vacuum bag, the food is put into a vacuum bag. Afterwards, air is drawn from the vacuum bag and an open end of the vacuum bag is sealed by a vacuum packing apparatus. However, some bags used in vacuum packaging are composed of two pieces of flat plastic films. The flat surfaces of the films are easy to be jointed together when the bag is evacuated, and thus makes air pockets be trapped in the bag, rendering the bag unsuitable for vacuum packaging of perishable items. In order to achieve a desirable vacuum, lots of efforts were made in the prior art.

One improved type of bags with embossments has been widely used in our daily life. A plurality of embossments each extends from the bottom to the open end of the bag are formed on the inner surface of the bag. When an item is vacuum packed, an air discharge path is defined by the embossments. However, when an item is put into the bag, an internal cavity may be formed between the bottom of the bag and the item. The air in the cavity will not be evacuated because the item obstructs the air discharge path. Thus a desirable vacuum cannot be obtained.

Another conventional type of vacuum bag is disclosed in Chinese patent publication No. 2736281, which has strip ridges (or grooves) on both plastic films thereof. The ridges (or the grooves) formed on the films are perpendicular with each other, and thus air flows along the channel defining by the ridges (or the grooves). However, forming the ridges (or the grooves) on both films makes the manufacturing process complex and costly.

Chinese Patent Publication No. 2312897 and U.S. Pat. No. RE 34929 disclose two conventional types of plastic bags for vacuum packing, which have ridges densely covered on one plastic film. When the bag is evacuated, air is extracted along the channels defined by two adjacent ridges. The channels are intercommunicated, so that there is no said internal cavity in the bag. However, in order to adapt for the use of sealer, the ridges formed on the bag are diagonal or curvilinear in the direction from the bottom to the open end of the bag, which results in that the air will not linearly extracted from the bag. So, it takes more time to evacuate the bag. Furthermore, the above described bags are of less strength, and they are easy to be destroyed when there is a breach on the film.

U.S. Pat. No. 6,991,109 titled “Vacuum Sealable Bag Apparatus and Method”, issued to Daniel P. Shannon on Jan. 31, 2006, also describes a storage bag with a venting strip formed therein to assist in evacuating the bag. The venting strip can be apertured and/or can have a textured or rough surface that creates channels between the inside surface of the storage bag and the venting strip, thereby allowing air to exit from the interior of the bag. However, the venting strip makes the manufacturing process complicated and is difficult to clean. Moreover, the strip may easily be cracked which makes the bag unsuitable for repeated use.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an improved plastic bag for vacuum packing such that air can be completely extracted from the bag.

It is another object of the present invention to provide a plastic bag for vacuum packing such that it takes less time to evacuate the bag.

It is still another object of the present invention to provide a plastic bag for vacuum packing with higher strength and durability, and lower cost.

It is a further object of the present invention to provide a plastic bag for vacuum packing such that the manufacturing process thereof is simplified.

To achieve the objects set forth above, the present invention provides a plastic bag for vacuum packing comprising a first film with flat surface and a second film with embossments, each of the films comprising an uniform inner surface which join together at least at opposite lateral sides thereof to define a chamber adapted to have an item disposed therein, and the embossments are formed on the inner surface of the second film. The embossments are arranged at intervals from each other and aligned along the extending direction of said lateral sides, thereby defining a list of embossments assembly (or referred as “assembly”). Two lists of said embossments assembly consist of a gas-exiting unit, where a first list of assembly and a second list of assembly are arranged at intervals from each other and staggered, so that each of the embossment of the second list of assembly faces to the clearance between the adjacent embossments of the first list of assembly. A Plurality of the gas-exiting units are arranged on the inner surface of the second film until the whole surface is covered.

In a preferable embodiment of the present invention, said embossment consists of more than one protuberance, and these protuberances are arranged at intervals and run parallel. Preferably, each of the protuberances is of the same length. In a preferable example of the present invention, at least two protuberances which locate outmost of the embossment are shorter than the other protuberances of the embossment, and said other protuberances are of the same length.

In another preferable embodiment of the present invention, the end of the embossment along the extending direction of said lateral sides is of semicircular, rectangular or triangular shape. Preferably, the end is semicircular.

The plastic bag for vacuum packing provided by the present invention only has one side of films to be embossed, and thus the manufacturing process thereof is simplified and at low cost. Further, the bag is easily to clean because of the absence of the venting strip. The embossments are spaced in longitudinal direction and staggered in transverse direction, and thus lots of intercommunicate channels are formed. Air exits from the bottom to the open end linearly or nearly linearly, so it takes less time to evacuate the bag. Moreover, the channels are intercrossed so as to eliminate the possibility to form any air pocket or internal cavity. Additionally, the embossments formed on the plastic bag provided by the present invention are arranged at intervals and staggered, so the strength of the bag is enhanced.

These and other objects, advantages and features of the present invention will become apparent by reference to the detailed description provided below which is to be considered in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

FIG. 1 illustrates a plastic bag according to one preferable embodiment of the present invention.

FIG. 2 is an enlarged view illustrating the circle portion shown in FIG. 1.

FIG. 3 is an enlarged view illustrating the embossments arranging manner in another example of the present invention.

FIG. 4 illustrates another plastic bag according to another preferable embodiment of the present invention.

FIG. 5 is an enlarged view illustrating the embossments arranging manner of the bag shown in FIG. 4.

FIG. 6 is a cross-sectional view illustrating the structure of the plastic bag shown in FIG. 4.

FIG. 7 schematically illustrates the arrangement of the embossments formed on the film of the bag shown in FIG. 4.

DETAILED DESCRIPTION OF A PREFERABLE EMBODIMENTS

FIG. 1 shows a plastic bag 10 according to a first embodiment of the present invention. The bag 10 comprises a first film 14 and a second film 12, joined together at the opposite lateral sides and a bottom side to define a chamber adapted to have an item disposed therein. The inner and outer surfaces of the first film 14 are both flat, but on the inner surface of the second film 12 are formed embossments. The embossments are arranged at intervals from each other and aligned along the extending direction of said lateral sides, thereby defining a list of embossments assembly (or referred as “assembly”). The clearance between the two adjacent embossments in a list of assembly is labeled as numeral 15. Two lists of said embossments assembly (for example, a first list assembly 16 and a second list of assembly 18) consist of a gas-exiting unit (such as unit 20), where a first list of assembly 16 and a second list of assembly 18 are arranged at intervals from each other and staggered, so that each of the embossment 13 of the second list of assembly 18 faces to the clearance 15 between the adjacent embossments of the first list of assembly 16. A plurality of the gas-exiting units 20 are arranged on the inner surface of the second film 12 until the whole surface is covered.

FIG. 2 shows an enlarged view of the circle portion shown in FIG. 1. In this embodiment, the embossment 13 is composed of six protuberances, arranged at intervals and run parallel, and these protuberances have the same length. The length of the embossment 13 along the extending direction of said lateral sides is labeled as “L” (that is the length of the protuberance 22); the length of the embossment 13 perpendicular to the extending direction of the lateral sides is labeled as “D”; the space between the first list of assembly 16 and the second list of assembly 18 is labeled as “S”; and the clearance between the two adjacent embossments in the same list of assembly is labeled as “H”. H and S have appropriate size, such that the second film 12 dose not close joint with the first film 14 until the air between the clearance 15, or the gap between the first list of assembly 16 and the second list of assembly 18, and the bottom of the bag is evacuated. Also, L and D depend on the length and width of the bag. For example, L is at least shorter than the length of the bag along the extending direction of the lateral sides, and D is at least shorter than the length of the bag perpendicular to the extending direction of the lateral sides. The person skilled in the art will easily determine the appropriate magnitudes of L, H, D and S based on limited simple experiments.

When the bag is evacuated, the air in the bag will exhaust through the channel (or referred as “groove”) formed by the embossment and the inner surface of the first film 14. Specifically, on the one hand, air will exit along the interspace between two adjacent protuberances (for example, the protuberance 22 and another protuberance 24), so the exiting path of the air is linear which accelerate the evacuation. On the other hand, when S is small enough, the air can also exit along the space between said two list of assembly (for example, the fist list of assembly 16 and the second list of assembly 18). Additionally, the clearances between adjacent embossments (such as clearance 15) are employed to achieve the interconnection of different grooves. When H is small enough, the clearance 15 will not close joint with the flat film while evacuating, so that any residual air can be effectively guided through the clearance 15. Further, the clearances between the two adjacent embossments in a list of assembly will not be arranged in a line paralleling the open end of the bag because of the stagger arrangement of the embossments. Thus, if the present invention is used in a conventional vacuum sealer, the circumstance that the air cannot be exhausted from the bag due to the press of the sealer can be avoided. Therefore, a conventional sealer can apply to the present invention.

FIG. 3 schematically shows the arrangement of the embossments formed on the inner surface of the second film 12 according to another preferable embodiment of the present invention. In this embodiment, the embossment 13′ only consists of one protuberance. The arrangement manner is the same as described above, simply the shape of the end of the protuberance along the extending direction of the lateral sides being semicircular which is different from the rectangular shape of the protuberance shown in FIG. 2. The semicircular end can reduce the friction with air and therefore speed up the air flow. Obviously, the end can be formed in triangle or any other shapes so long as to assist the air flow, or the whole protuberance can be formed as a cylinder with slippery surface.

Referring now to FIG. 4 which shows another plastic bag according to another preferable embodiment of the present invention. The bag 40 comprises a first film 34 and a second film 32, joined together at the opposite lateral sides and a bottom side to define a chamber adapted to have an item disposed therein. The inner and outer surfaces of the first film 34 are both flat, but on the inner surface of the second film 32 are formed a plurality of embossments 33. As shown in FIG. 5-7, the embossment 33 consists of eight protuberances 37, arranged at intervals and run parallel. The four outmost protuberances (such as protuberance 371, 372, 377 and 378) are shorter than the other four protuberances (such as protuberance 373, 374, 375 and 376), and said other four protuberances have the same length. Adjacent protuberances form a groove 36 provided for air flow.

In this example, referring to FIG. 7, the embossments are arranged at intervals from each other and aligned along the extending direction of said lateral sides, thereby defining a list of embossments assembly (or referred as “assembly”). The clearance between the two adjacent embossments in a list of assembly is labeled as numeral 35. Two lists of said embossments assembly (for example, a first list assembly 50 and a second list of assembly 52) consist of a gas-exiting unit, where a first list of assembly 50 and a second list of assembly 52 are arranged at intervals from each other and staggered, such that each of the embossment 33 of the second list of assembly 52 faces to the clearance 35 between the adjacent embossments of the first list of assembly 50. A plurality of the gas-exiting units are arranged on the inner surface of the second film 32 until the whole surface is covered.

When the bag is evacuated, the air in the bag will exhaust through the channel (or referred as “groove”) formed by the embossments and the inner surface of the first film 34. Specifically, air exits along the space between said two list of assembly (for example, the fist list of assembly 50 and the second list of assembly 52), so the exiting path of the air is linear which accelerate the evacuation. Also, the clearances between adjacent embossments (such as clearance 35) are employed to achieve the interconnection of different grooves. When the area of the clearance 35 is small enough, it will not close joint with the flat film while evacuating, so that any residual air can be effectively guided through the clearance 35. Further, the clearances between the two adjacent embossments in a list of assembly will not be arranged in a line paralleling the open end of the bag because of the stagger arrangement of the embossments. Thus, if the present invention is used in a conventional vacuum sealer, the circumstance that the air cannot be exhausted from the bag due to the press of the sealer can be avoided. Therefore, a conventional sealer can apply to the present invention.

As known to the person skilled in the art, the embossments or the protuberances on the inner surface of the second film can be formed by compression molding or laminating method. The film can be made of polypropylene, polyethylene, high-density polyethylene, nylon or mixtures thereof.

The plastic bag for vacuum packing provided by the present invention has embossments which space in longitudinal direction and stagger in transverse direction formed on the inner surface, and thus lots of intercommunicate channels are formed so as to eliminate the possibility to form any air pocket or internal cavity. Meanwhile, air linearly exits from the bottom to the open end, so it takes less time to evacuate the bag. Further, the bag only has one film be embossed, and thus the manufacturing process thereof is simplified and at low cost, and the bag is easy to wash. Moreover, the strength of the bag provided by the present invention is enhanced, especially the anti-avulsion capability is well improved.

The bag can be made as individual bags or as continuous bag rolls. In many cases, the roll consists of a continuous tube of sheet material which is cut to a desired length and can be heat seal on an open end of the tube to form a bag.

It should be understood that various alternatives to the embodiments of the present invention described herein may be employed in practicing the invention. It is intended that the following claims define the invention and that structures within the scope of these claims and their equivalents be convered thereby. 

1. A plastic bag for vacuum packing comprising a first film with flat surface and a second film with embossments, each of said films comprising an uniform inner surface which join together at least at opposite lateral sides thereof to define a chamber adapted to have an item disposed therein, and said embossments are formed on the inner surface of said second film, wherein the embossments are arranged at intervals from each other and aligned along the extending direction of said lateral sides, thereby defining a list of embossments assembly; two lists of said embossments assembly consist of a gas-exiting unit, where a first list of embossments assembly and a second list of embossments assembly are arranged at intervals from each other and staggered, such that each of the embossment of the second list of embossments assembly faces to the clearance between the adjacent embossments of the first list of embossments assembly; a plurality of said gas-exiting units are arranged on the inner surface of said second film until the whole surface is covered.
 2. The plastic bag for vacuum packing of claim 1 wherein each of the embossments consists of more than one protuberance and these protuberances are arranged at intervals and run parallel.
 3. The plastic bag for vacuum packing of claim 2 wherein the embossments consists of four protuberances.
 4. The plastic bag for vacuum packing of claim 2 wherein the protuberances have the same length.
 5. The plastic bag for vacuum packing of claim 2 wherein at least two protuberances which locate outmost of the embossment are shorter than the other protuberances of the embossment, and said other protuberances are of the same length.
 6. The plastic bag for vacuum packing of claim 1 wherein each of the clearances between the adjacent embossments in said list of embossments assembly has the same length.
 7. The plastic bag for vacuum packing of claim 1 wherein the shape of the end of the embossment along the extending direction of said lateral side is semicircle, rectangle or triangle.
 8. The plastic bag for vacuum packing of claim 2 wherein the shape of the end of the embossment along the extending direction of said lateral side is semicircle, rectangle or triangle.
 9. The plastic bag for vacuum packing of claim 2 wherein the shape of the end of the embossment along the extending direction of said lateral side is semicircle.
 10. The plastic bag for vacuum packing of claim 1 wherein said gas-exiting units are arranged at regular intervals. 